We had another Velocity collapse today at the Cal state record due to a Velocity hitting the wake turbulence of a canopy ahead of him. The canopy collapsed on one side at about 200 feet, spun the person at least 180 degrees, then reinflated at about 30 feet. Jack Gramley was in the process of calling for help when it reinflated and landed the person without injury (fortunately.)

Any canopy can be collapsed by sufficient turbulence, but this is the third Velocity I've seen collapse due to wake turbulence in otherwise smooth air. Might be a good idea to consider whether to use a canopy like the Velo during dives where traffic makes wake turbulence more likely.

Why are the organizers allowing such an aggressive canopy on such a large formation?

Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and is tough to fly through traffic (without having to hang in serious brakes or trying to weave through the pattern with speed).

The only time I've ever had problems with a Velo's stability is going through turbulence in moderate to deep brakes or flying one where the trim was going out. And in the case of a high performance canopy, what I consider out of trim is what most jumpers wouldn't even notice on their Sabre2s or Pilots.

>Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and >is tough to fly through traffic (without having to hang in serious brakes or trying to >weave through the pattern with speed).

Agreed. And for the "bigger" stuff they are requiring lighter wing loadings and less twitchy canopies. (I know, it's odd that a 200 way is now considered "not that big.")

Thanks for posting that. There's another reason to use an RSL. Funny how people think they're too good to need one.

This summer I saw a very experienced jumper jumping a moderately loaded nine cell have a partial collapse, 180 turn and reinflation at low altitude due to wake turbulence. Maybe this is an issue that needs more awareness. The strength of wake turbulence is influenced by several different factors, and so are our canopies' reactions to it. Our modern canopies have little tolerance for many things. Wake turbulence might be one of them.

>Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and >is tough to fly through traffic (without having to hang in serious brakes or trying to >weave through the pattern with speed).

Agreed. And for the "bigger" stuff they are requiring lighter wing loadings and less twitchy canopies. (I know, it's odd that a 200 way is now considered "not that big.")

While it's smaller than 400, there haven't been very many formations >=200 completed.

>Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and >is tough to fly through traffic (without having to hang in serious brakes or trying to >weave through the pattern with speed).

Agreed. And for the "bigger" stuff they are requiring lighter wing loadings and less twitchy canopies.

I thought the wing loadings were requirements too, but I just checked the Dubai 500 application and it says,

Quote:

Larger canopies with slower descent rates are highly recommended. Please consider jumping a canopy that puts you in a wingloading between 1.25 and 1.75 for these events.

Quote Larger canopies with slower descent rates are highly recommended. Please consider jumping a canopy that puts you in a wingloading between 1.25 and 1.75 for these events.

So, only recommended, not required. Perhaps that should change.

Half the organizers exceed that recommendation. They're not going to make it a requirement.

Actually, of the few bigways I've done - having a wide variety of wingloadings helped spread out the landings in time. The higher wingloadings land before the lower ones do. As long as you've got adequate separation at pull-time, having a wide range of wingloadings is one way to reduce the risk of collision.

Even my docile canopies are loaded on the "heavy" side. I was surprised to see all the organizers beat me me down the last time I was at a p3 camp.

"Maybe this is an issue that needs more awareness." I'll second that. Pilots are taught about wake turbulence, but skydivers aren't. I'd say that information about wake turbulence should be included in the training along with info about turbulence from wind coming over buildings, etc.

>Half the organizers exceed that recommendation. They're not going to make it a requirement.

They're working on that - getting sponsored and semi-sponsored medium performance mains that several team captains will be jumping. The video team is getting bigger canopies as well, since giving them all much larger canopies is a way to "take them out of the equation" so to speak. But I don't think they have a final plan yet.

I doubt it was a velocity specific problem. Any canopy will collapse under wake turbulence. Smaller canopies do have a higher pressurisation because of higher airspeeds, but loosing 1/4 of a 90 sq/ft canopy is a lot less available wing then loosing 1/4 of a 150 sq/ft canopy. Canopy choice and especially size requires a lot of responsibility, you need to take into account what you are going to do with that canopy. Flying a highly wingloaded canopy on big ways, is probably not the best idea, or if so dont land where everyone else is landing. People now a days downsize without thinking about things fully, just being able to land a small canopy isnt everything to consider. Most dont realise your EP's become more important to have down with a small canopy, Pattern, traffic, ability to put yourself out of traffic ect, ect, ect. Ive heard the excuse I was jumping an 84 I had to land then, too many times. Most dont realise they can stay up, even with a small canopy. Learn your canopy people! learn landing separation, fly a good pattern, and when in doubt land at the alternate landing area. And most of all from this situation everyone should know where not to fly in relation to other canopies. These are all things this person, or anyone that jumps a canopy, let alone a small canopy should know. Especially before someone decides to downsize. I still dont think its a Velocity problem, Im pretty sure any canopy would have done this.

True, but some are certainly more sensitive than others. (The old Nova was a famous example.) From what I've seen, Velos are unforgiving of wake turbulence, something most other canopies handle without too much trouble.

>I still dont think its a Velocity problem, Im pretty sure any canopy would have done this.

Have you seen other canopies malfunction when flying through wake turbulence?

>Most dont realise they can stay up, even with a small canopy.

True - but when you have 100 other people who are also trying to stay up your options are a lot more limited. If you have a Velocity 84, you're not going to outfloat the guy with a Pilot 150 who is _also_ trying to stay up.

>Half the organizers exceed that recommendation. They're not going to make it a requirement.

They're working on that - getting sponsored and semi-sponsored medium performance mains that several team captains will be jumping. The video team is getting bigger canopies as well, since giving them all much larger canopies is a way to "take them out of the equation" so to speak. But I don't think they have a final plan yet.

Leaders should lead by example. These are guys working in the sport, it should be no problem for them to obtain more suitable equipment. Especially if they are expecting the guys who are already paying to work their way through the camps, and do the big ways to do the same, who are less likely to have more suitable gear as readily available to them.

Full face helmets and AADs are mandatory for big ways. Why not specified wing loadings? I heard of one guy getting benched at the recent CSR 200-way for having an older rig with poor pin protection. When you get to these sizes everything is about safety and logistics. I don't really buy the separation argument. There's should be enough range between 1.25 to 1.75 without having people outside that. I appreciate there's a risk with unfamiliar gear, but it's easy to get familiar on gear before an event. Is it that much effort? People will argue that their high performance main opens better than anything else, but is it really worth having people at the extreme end of the performance envelope at such high profile, critical events? It seems the only argument for exceeding wing loading guidelines is inconvenience and that shouldn't be a reason.

"Maybe this is an issue that needs more awareness." I'll second that. Pilots are taught about wake turbulence, but skydivers aren't. I'd say that information about wake turbulence should be included in the training along with info about turbulence from wind coming over buildings, etc.

Very true. Back in high school when I was going for my private pilot license (never got it, paying for college took priority), I was learning to fly at Quantico in Virginia. HMX-1 is stationed there which means they've got C-17s and C-130s constantly flying in and out depending on the president's travel schedule.

One day I was returning on a solo flight and entered the pattern behind a C-130. I was about a mile back and at about 1500 feet when all of a sudden the plane got buffeted and thrown into a dive. I quickly recovered and got back into downwind, now probably 1.25mi back. Same thing happened. Took about a second for it to click that his wake was frickin huge and I notified the tower I was heading to the pattern entry point to give my self some space.

Wake turbulence is definitely taught during ground school and the entire PPL progression. It should be included in the AFF program since our wings are susceptible to it and if it occurs it'll most likely be during the pattern where altitude is minimal.

I doubt it was a velocity specific problem. Any canopy will collapse under wake turbulence. Smaller canopies do have a higher pressurisation because of higher airspeeds, but loosing 1/4 of a 90 sq/ft canopy is a lot less available wing then loosing 1/4 of a 150 sq/ft canopy.

I asked previously if either the lead or trailing canopy were flying in brakes, but nobody answered.

I suspect that the lead canopy in brakes creates an ever larger wake, and equally - the trail canopy in deep brakes is even more susceptible to the effect of the turbulence. The latter may be more true with cross-braced canopies with their very small open cells.

This would create the double-whammy when a canopy pilots first instinct is to slow down.

True, but some are certainly more sensitive than others. (The old Nova was a famous example.) From what I've seen, Velos are unforgiving of wake turbulence, something most other canopies handle without too much trouble.

Are you really comparing a Nova to the velocity? Velocities have a long history of being a good canopy, and yes I have seen many canopies collapse, most of them high enough to reinflate, I see Tandem mains do it all the time, precision, PD and Icarus models. There was a crossfire 1 fatality at the pond national at the ranch where the canopy completely collapsed, yet crossfires continue to safely land skydivers every day.

Quote:

True - but when you have 100 other people who are also trying to stay up your options are a lot more limited. If you have a Velocity 84, you're not going to outfloat the guy with a Pilot 150 who is _also_ trying to stay up.

Ill take that challenge, I have a long history of doing video, big ways and 4way, I always made it a priority to have everyone I filmed land before me. Bring your pilot 150 and lets have a lift contest, Ill stay with you all day.

This happened to me down in sebastian earlier this year. After talking to some very experienced canopy pilots, the best guess is wake turbulence. The canopy in front of me however is pretty far, even for a go pro video, and we are on our downwind leg.

>Do you have data to show that Velos are less stable than other canopies?

Data? No. But a handful of videos showing collapses - some recoverable, some leading to cutaways. And a fair number more of stories about wake turbulence.

Keep in mind that Glide Path claimed there was no data to prove that the Nova was less stable either; they said any canopy could collapse (which is certainly true.) But they did seem a lot worse than other canopies.

1 - Speed increases pressure and possibly makes the canopy more resistant to turbulence induced collapse. The opposite is true with less speed.

2 - The higher loaded you are, the worse the results of a collapse are going to be.

I'm with the not believing it's Velocity issue crowd.

I had a Jonathan 136 collapse on me from wake turbulance at 3,000 feet. Half of the parachute was folded under and in the lines. It was 'violent' and had I been jumping something smaller it would've been even more so.

I got to test this theory years later on my Velo. Yes, it rocked me when I flew in wake turbulence. I was doing this on purpose, so I was very high. But in both instances I was flying in deeper than half brakes.

My conclusion is that flying any small canopy in deep brakes in turbulent air is risky. Even more so at low altitude. One reason I really don't care for the deep brakes to front riser method for setting up a swoop.

As far as the Velocity. Doesn't this canopy hold a good portion of the market? Meaning there's a lot of them out there. So in the few instances that this has happened the chances are probably pretty good that it's a velo. A friend of mine did have an FX collapse on him while in the pattern that resulted in line-twists. This was some 10-12 years ago.

1 - Speed increases pressure and possibly makes the canopy more resistant to turbulence induced collapse. The opposite is true with less speed.

2 - The higher loaded you are, the worse the results of a collapse are going to be.

I'm with the not believing it's Velocity issue crowd.

I had a Jonathan 136 collapse on me from wake turbulance at 3,000 feet. Half of the parachute was folded under and in the lines. It was 'violent' and had I been jumping something smaller it would've been even more so.

I got to test this theory years later on my Velo. Yes, it rocked me when I flew in wake turbulence. I was doing this on purpose, so I was very high. But in both instances I was flying in deeper than half brakes.

My conclusion is that flying any small canopy in deep brakes in turbulent air is risky. Even more so at low altitude. One reason I really don't care for the deep brakes to front riser method for setting up a swoop.

As far as the Velocity. Doesn't this canopy hold a good portion of the market? Meaning there's a lot of them out there. So in the few instances that this has happened the chances are probably pretty good that it's a velo. A friend of mine did have an FX collapse on him while in the pattern that resulted in line-twists. This was some 10-12 years ago.

You forgot to mention the planform which will greatly effect the result of turbulence. Its funny that you mention that Jonathan because when I read this topic I remembered how my Jonathan was particularly suceptible to collapse

Turbulence isn't static; it's not just sitting there, waiting. All turbulence is is moving air. Wind is air all moving in the same direction; turbulence is wind that's moving in different directions depending on where you are. If you are standing still with respect to the average wind you feel very little turbulence. If you're moving you feel it as you move from one area of wind to another. The faster you go, the faster the winds change direction and the more turbulence you feel.

When airplanes encounter severe turbulence they slow down to avoid overstressing their flight surfaces. The slower the aircraft goes, the less change it sees per unit of time, and the less force that wind can apply to the aircraft. However, slowing down too much (say to near stall) also isn't a good idea - if you are 10 knots above stall, then flying into a region with a 12 knot gust from behind you will stall the airplane.

Canopies can't change their airspeed without distorting their airfoil shapes, and most modern canopies are most stable either at full flight or with very slight brakes applies. Thus it's generally better to be flying at full flight (or close to it.) But flying faster to "keep your wing pressurized" and/or "cut through the turbulence faster" doesn't work.

Still, a given size of gust will cause a lower change in angle of attack for a wing at higher speed. In that sense one can 'cut through' turbulence -- less likely for a down gust to unload the front of the wing and collapse it.

On the other hand, more speed gives less time for the canopy to adapt to a new angle of attack and thus can 'get hit' by turbulence if flying faster instead of having time to react and adapt to the new conditions if flying slower. Which could be good or bad depending on the situation. (Eg if you get hit by some idealized upwards gust before hitting a following downwards gust -- the down gust isn't as extreme a change if the wing hasn't already reacted to the up gust. In that particular situation, more speed is again better. But if it is a down gust followed by more down gust, the wing moving with the conditions can be better.)

I think it will depend on the exact natures and scale of the turbulence, which factor wins out. Still, I think extra speed tends to win out as better. (At least as long as one doesn't actually have a collapse -- then slower can be better in many circumstances.)

[replyYou forgot to mention the planform which will greatly effect the result of turbulence. Its funny that you mention that Jonathan because when I read this topic I remembered how my Jonathan was particularly suceptible to collapse Given that ellipticals are a bit more 'unstable', I assume you mean the results of turbulence can be more dramatic if you're not on it right away. I don't know how much planeform lends a canopy to be more prone to collapse or not.

I didn't feel my Jonathan was any more prone to collapse. I only had the one instance and that was the result of a few factors. Mostly my fault.

Just a point. There is a difference between collapsing and just getting blown around by turbulence. Most 'collapses' I've heard people talk about are usually the latter when I've seen them. That's not to say it matters much to the person under canopy, Since both experiences can be iffy. But all out collapses are pretty rare all things considered.

>Still, a given size of gust will cause a lower change in angle of attack for a wing at >higher speed.

But a greater force. Which is why aircraft generally slow down when encountering turbulence.

Aircraft, of course, have an advantage that we don't - their wings are rigid, and even the weakest rigid wing can withstand some negative G's. Which is why it's pretty important for us to avoid negative loading.